Human uvula: Characterization of resident leukocytes and local cytokine production

Upper airway infections often lead to macroscopic changes in the architectu re of the uvula. Using immunomorphometric analysis, we investigated the fre quency and distribution of immune cells and of cytokine-producing cells in uvular samples. Tissue macrophages, alpha beta T cells, gamma delta T cells , and B cells were, in declining order, the main cell populations, gamma de lta T cells and B cells exhibited reciprocal localization, with almost all gamma delta T cells residing in the vicinity of the epithelium, and all B c ells in the glandular area. The presence of cells expressing the suppressor phenotype CD8(+)CD28(-) alpha beta T cells is suggested. Fifteen to twenty -five percent of the immune cells expressed the down-regulatory cytokine tu mor growth factor beta. Most macrophages were located subepithelially, in t he vicinity of the basal lamina. The composition and cytokine profile of le ukocytes in the tissue suggest that the uvula may be a site, additional to the jejunal mucosa, for induction of mucosal tolerance to inhaled and inges ted antigens. Concomitantly, the uvula appears to be protected from invasio n of microbial pathogens by a subepithelial barrier of macrophages and gamm a delta T cells.